Neural dynamics of predictive timing and motor engagement in music listening.

Why do humans spontaneously dance to music? To test the hypothesis that motor dynamics reflect predictive timing during music listening, we created melodies with varying degrees of rhythmic predictability (syncopation) and asked participants to rate their wanting-to-move (groove) experience. Degree of syncopation and groove ratings are quadratically correlated. Magnetoencephalography data showed that, while auditory regions track the rhythm of melodies, beat-related 2-hertz activity and neural dynamics at delta (1.4 hertz) and beta (20 to 30 hertz) rates in the dorsal auditory pathway code for the experience of groove. Critically, the left sensorimotor cortex coordinates these groove-related delta and beta activities. These findings align with the predictions of a neurodynamic model, suggesting that oscillatory motor engagement during music listening reflects predictive timing and is effected by interaction of neural dynamics along the dorsal auditory pathway.

What Do We Know About Medical Cannabis in Neurological Disorders and What Are the Next Steps?

Medical use of cannabis has been receiving growing attention over the last few decades in modern medicine. As we know that the endocannabinoid system is largely involved in neurological disorders, we focused on the scientific rationale of medical cannabis in three neurological disorders: amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease through pharmacological plausibility, clinical studies, and patients' view. Clinical studies (randomized controlled trials, open-label studies, cohorts, and case reports) exploring medical cannabis in these disorders show different results depending on the methods and outcomes. Some show benefits on motor symptoms and others on non-motor symptoms and quality of life. Concerning patients' view, several web surveys were collected, highlighting the real use of cannabis to relieve symptoms of neurological disorders, mostly outside a medical pathway. This anarchic use keeps questioning particularly in terms of risks: consumption of street cannabis, drug-drug interactions with usual medical treatment, consideration of medical history, and adverse reactions (psychiatric, respiratory, cardiovascular disorders, etc.), underlining the importance of a medical supervision. To date, most scientific data support the therapeutic potential of cannabis in neurological disorders. As far as patients and patients' associations are calling for it, there is an urgent need to manage clinical studies to provide stronger evidence and secure medical cannabis use.

Neural correlates of rhythmic rocking in prefrontal seizures.

OBJECTIVES: Rhythmic body rocking movements may occur in prefrontal epileptic seizures. Here, we compare quantified time-evolving frequency of stereotyped rocking with signal analysis of intracerebral electroencephalographic data. METHODS: In a single patient, prefrontal seizures with rhythmic anteroposterior body rocking recorded on stereoelectroencephalography (SEEG) were analyzed using fast Fourier transform, time-frequency decomposition and phase amplitude coupling, with regards to quantified video data. Comparison was made with seizures without rocking in the same patient, as well as resting state data. RESULTS: Rocking movements in the delta (∼1 Hz) range began a few seconds after SEEG onset of low voltage fast discharge. During rocking movements: (1) presence of a peak of delta band activity was visible in bipolar montage, with maximal power in epileptogenic zone and corresponding to mean rocking frequency; (2) correlation, using phase amplitude coupling, was shown between the phase of this delta activity and high-gamma power in the epileptogenic zone and the anterior cingulate region. CONCLUSIONS: Here, delta range rhythmic body rocking was associated with cortical delta oscillatory activity and phase-coupled high-gamma energy. These results suggest a neural signature during expression of motor semiology incorporating both temporal features associated with rhythmic movements and spatial features of seizure discharge.

Natural rhythms of periodic temporal attention.

That attention is a fundamentally rhythmic process has recently received abundant empirical evidence. The essence of temporal attention, however, is to flexibly focus in time. Whether this function is constrained by an underlying rhythmic neural mechanism is unknown. In six interrelated experiments, we behaviourally quantify the sampling capacities of periodic temporal attention during auditory or visual perception. We reveal the presence of limited attentional capacities, with an optimal sampling rate of ~1.4 Hz in audition and ~0.7 Hz in vision. Investigating the motor contribution to temporal attention, we show that it scales with motor rhythmic precision, maximal at ~1.7 Hz. Critically, motor modulation is beneficial to auditory but detrimental to visual temporal attention. These results are captured by a computational model of coupled oscillators, that reveals the underlying structural constraints governing the temporal alignment between motor and attention fluctuations.